Kinases catalyze the transfer of the γ-phosphate from adenosine 5´-triphosphate (ATP) to proteins, lipids, sugars, or other acceptors. This process, termed phosphorylation, forms the cornerstone of most signal transduction cascades. Kinases regulate virtually all cellular activities and have important roles in cell survival, proliferation, differentiation, and migration. Dysregulated kinase activity contributes to a wide range of human disorders including cancer. As such, kinases are currently prime pharmacological targets, and simple, accurate assays used to measure kinase activity are crucial for rapid drug discovery.
Currently available kits typically fall into two general categories. Most are kinase-specific and are based on antibodies that recognize phosphorylated products. In contrast, universal kinase assays are designed to measure the common donor substrate ATP, or the product ADP, and can be used for virtually all kinases. Because of their flexibility, universal assays are desirable for high-throughput screening (HTS) and are the focus of this article.
A new Universal Kinase Activity Kit (Catalog # EA004) has been developed by R&D Systems. This assay utilizes a specific phosphatase to release the β-phosphate from adenosine 5´-diphosphate (ADP) produced during the kinase reaction. The amount of free phosphate is then measured and is used as an indicator of kinase activity. This new assay offer several advantages over currently available universal kinase assays.